diff --git a/README.md b/README.md
index c809036..a0e1898 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,8 @@ Eebie is a very small C99 library for reading and writing EBML files, namely Mat
 
 The library is meant to be embedded directly into another project.
 
+TODO: signed integer writing
+
 ## Reading example
 
     #include"eebie/reader.h"